Growthspurt – Measuring and tracking

Two thirteen-year-old players can stand side by side on the pitch and still be years apart in their physical development. One has not yet started the growth spurt, the other is in the middle of it. For coaches, trainers and parents, that difference matters. It determines what a child can handle, where they are at risk and how best to train them.

What is the growth spurt?

Children do not grow at an even pace. After childhood, when height increases fairly steadily, puberty brings a period of accelerated growth: the growth spurt. The moment at which a child grows fastest is called the peak of the growth spurt, or Peak Height Velocity (PHV). The age at which that peak occurs is called the APHV: Age at Peak Height Velocity.

Girls reach the peak at around twelve on average, boys at around fourteen. These are averages. For one child the peak comes a year or two earlier, for another a year or two later. It is precisely this spread that makes measuring worthwhile.

Three growth periods

The Athletic Skills Model (ASM) divides development around the growth spurt into three periods:

• P1 · Growth spurt – preparation period. The child grows steadily. This is a good period for varied movement and learning many different skills.
• P2 · Growth spurt – accelerated growth period. The growth spurt. Bones grow faster than muscles and tendons. The child may become temporarily a little clumsier and is more susceptible to overload.
• P3 · Growth spurt – stabilisation period. Growth slows down and stabilises. Strength and load capacity can be built up again step by step.

Calendar age does not tell the whole story

In sport, children are usually grouped by year of birth. Within such a group there can be large differences in biological age: how far a child has developed physically. An early-maturing player is often taller, stronger and faster. That can look like an advantage in talent, when it is mainly an advantage in growth. A late-maturing player, on the other hand, runs the risk of being underestimated.

If you only look at performance, you will not see that difference. If you know which growth phase a child is in, you can put performance in context and avoid writing off talent too early.

Why the growth spurt needs extra attention

During the growth spurt the body changes quickly. Bones get longer, while muscles and tendons still have to catch up. The growth plates, where the bone grows, are vulnerable during this period. Repeated load with a lot of jumping, sprinting or heavy strength exercises can then cause complaints in, for example, the knee, heel or back.

In addition, a child has to learn to control their new body length and levers. Movements that used to be smooth may temporarily be harder. That is normal and part of growing.

This does not mean that children in the growth spurt should move less. It means that the type of load matters: plenty of variety, attention to technique and coordination, strength work with body weight, sufficient recovery, and caution with large volumes of jumping and landing work and heavy weights.

How do you calculate the growth phase?

The peak of the growth spurt can only be determined with certainty once it has passed. That is why it is estimated in advance. A widely used method is the Mirwald method. It requires four measurements:

• height;
• sitting height (measured from seat to top of the head);
• weight;
• age at the time of measurement, and sex.

The ratio between leg length and trunk length, together with weight and age, produces an estimate of how far a child is from the peak. From this, the expected age and date of the peak can also be calculated, and therefore the growth phase.

It remains an estimate, with a margin of roughly six months to a year. One measurement gives a first impression. Several measurements in succession make the picture more reliable.

Why measure regularly?

Growth is best followed by measuring more often. We recommend measuring roughly every three to four months, preferably at a fixed time of day and in the same way. This lets you see:

• when growth accelerates, so you can see the growth spurt coming;
• whether the estimated peak matches actual growth;
• when growth slows down again and a child moves into the next phase;
• how a child compares to the rest of the team.

For a coach, this means training can be adjusted for each child, rather than for the whole group at once. For parents, it gives insight into what their child is going through, and an explanation for temporary clumsiness or tiredness.

Tips for a good measurement

• Measure barefoot or in socks, with the heels against the wall and looking straight ahead.
• Measure sitting height on a stool with a flat seat, sitting upright. Subtract the height of the stool.
• Weigh in light clothing and without shoes.
• Record to the nearest millimetre (height) and tenth of a kilo (weight).
• Always measure at roughly the same time of day. Children are slightly taller in the morning than in the evening.

Get started

With the growth calculation on this site you enter the measurements for each child. The calculation immediately shows the estimated peak of the growth spurt, the biological age and the growth phase. For each phase you can see what you can and should rather not do in training. This turns a few measurements a year into a practical tool for healthy and responsible development.

The calculation is an estimate and does not replace medical advice. If a child has persistent pain in, for example, the knee, heel or back, consult a (sports) doctor or physiotherapist.